This article concerns Windows users only
It depends on the version of host application (DAW) you use. 64-Bit version of Windows can handle both; 32-Bit and 64-Bit DAWs. Therefore, you need to check whether the host application you use is 32-Bit or 64-Bit, and choose the corresponding plugin installer.
On 32-Bit version of Windows you can use only 32-Bit DAWs, so the plug-ins should also be installed as 32-Bit binaries.